Zirconia , ZrO2, is a widely used ceramic material exhibiting excellent properties such as low thermal conductivity, high coefficient of thermal expansion, high thermal stability, high oxygen ion conductivity, high strength, high fracture toughness and high thermal shock resistance enabling it to be used as thermal barrier coating, cutting tools, refractory material, as catalyst/catalyst support [1]. The crystal phases of zirconia can be classified as three kinds: monoclinic, tetragonal and cubic. It has been proved that toughness of zirconia will increase if phase transformation from tetragonal to monoclinic zirconia occurs [2]. Many properties of nanocrystalline zirconia are fundamentally different from those of conventional micrometersized zirconia because of the small crystallite dimension. They exhibit increased strength and ductility, enhanced diffusivity, and increased edges and corners, all beneficial for applications in catalysis, electronics, and ceramics [3]. Nano-sized zirconia have been prepared using various methods including sol-gel, precipitation, hydrothermal methods, gas phase synthesis, microwave, sonochemical, and microemulsion methods. The purpose of the present study is to fabricate zirconia nanopowders via a versatile, clean, and non-toxic method based on microwave irradiation process. The nanoparticles have been characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy and ultraviolet-visible spectroscopy ( UV). The optical properties of prepared nanoparticles have been studied as well.

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